1,2,3,3,3-Pentafluoropropene Production Processes

ABSTRACT

A process is disclosed for making CF 3 CF═CHF. The process involves reacting CF 3 CClFCCl 2 F with H 2  in a reaction zone in the presence of a catalyst to produce a product mixture comprising CF 3 CF═CHF. The catalyst has a catalytically effective amount of palladium supported on a support selected from the group consisting of alumina, fluorided alumina, aluminum fluoride and mixtures thereof and the mole ratio of H 2  to CF 3 CClFCCl 2 F fed to the reaction zone is between about 1:1 and about 5:1. 
     Also disclosed are azeotropic compositions of CF 3 CClFCCl 2 F and HF and azeotropic composition of CF 3 CHFCH 2 F and HF.

This application is a Divisional application of pending U.S. patentapplication Ser. No. 13/539,963 filed Jul. 2, 2012, which is aDivisional of U.S. patent application Ser. No. 12/301,065 filed Nov. 17,2008, now U.S. Pat. No. 8,263,816, which was a national filing under 35U.S.C. 371 of International Application No. PCT/US07/14646 filed Jun.22, 2007, and claims priority of U.S. Provisional Application No.60/816,649 filed Jun. 27, 2006.

FIELD OF THE INVENTION

The present invention relates to processes that involve the productionof halogenated hydrocarbon products comprising1,2,3,3,3-pentafluoropropene.

BACKGROUND OF THE INVENTION

As a result of the Montreal Protocol phasing out ozone depletingchlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs),industry has been working for the past few decades to find replacementrefrigerants. The solution for most refrigerant producers has been thecommercialization of hydrofluorocarbon (HFC) refrigerants. The newhydrofluorocarbon refrigerants, HFC-134a being the most widely used atthis time, have zero ozone depletion potential and thus are not affectedby the current regulatory phase out as a result of the MontrealProtocol. The production of other hydrofluorocarbons for use inapplications such as solvents, blowing agents, cleaning agents, aerosolpropellants, heat transfer media, dielectrics, fire extinguishants andpower cycle working fluids has also been the subject of considerableinterest.

There is also considerable interest in developing new refrigerants withreduced global warming potential for the mobile air-conditioning market.

HFC-1225ye, having zero ozone depletion and a low global warmingpotential, has been identified as a potential refrigerant. U.S. Pat. No.5,396,000 discloses a process for producing HFC-1225ye bydehydrofluorination of CF₃CFHCF₂H (HFC-236ea). There is a need for newmanufacturing processes for the production of HFC-1225ye.

SUMMARY OF THE INVENTION

The present invention provides a process for making HFC-1225ye.

The process comprises reacting CF₃CClFCCl₂F (CFC-215bb) with H₂ in areaction zone in the presence of a catalyst comprising a catalyticallyeffective amount of palladium supported on a support selected from thegroup consisting of alumina, fluorided alumina, aluminum fluoride andmixtures thereof, to produce a product mixture comprising HFC-1225ye,wherein the mole ratio of H₂ to CF₃CClFCCl₂F fed to the reaction zone isbetween about 1:1 and about 5:1.

The present invention also provides a composition comprising (a)CF₃CClFCCl₂F and (b)HF; wherein the HF is present in an effective amountto form an azeotropic combination with the CF₃CClFCCl₂F.

The present invention also provides a composition comprising (a)1,1,1,2,3-pentafluoropropane and (b)HF; wherein the HF is present in aneffective amount to form an azeotropic combination with the1,1,1,2,3-pentafluoropropane.

DETAILED DESCRIPTION

The present invention provides a process for making HFC-1225ye fromCFC-215bb by reacting CFC-215bb with hydrogen in a reaction zone over asuitable catalyst. HFC-1225ye may exist as one of two configurationalisomers, E or Z. HFC-1225ye as used herein refers to the isomers,E-HFC-1225ye (CAS reg no. 5595-10-8) or Z-HFC-1225ye (CAS reg. no.5528-43-8), as well as any combinations or mixtures of such isomers.

CFC-215bb can be prepared from a variety of starting materials. Forexample, CF₃CCl═CCl₂ can be converted to CFC-215bb as disclosed in U.S.Pat. Nos. 2,466,189 and 2,437,993, which are incorporated herein byreference.

Catalysts suitable for carrying out the process of making HFC-1225yefrom CFC-215bb in accordance with this invention comprise palladium andmay optionally comprise additional Group VIII metals (e.g., Pt, Ru, Rhor Ni). The palladium is supported on alumina, fluorided alumina,aluminum fluoride or a mixture thereof. The palladium-containingmaterial used to prepare the catalyst is preferably a palladium salt(e.g., palladium chloride). Other metals, when used, may be added to thesupport during the preparation of the catalyst.

The supported metal catalysts may be prepared by conventional methodsknown in the art such as by impregnation of the carrier with a solublesalt of the catalytic metal (e.g., palladium chloride or rhodiumnitrate) as described by Satterfield on page 95 of HeterogenousCatalysis in Industrial Practice, 2^(nd) edition (McGraw-Hill, New York,1991). Palladium supported on alumina is available commercially. Anothersuitable procedure for preparing a catalyst containing palladium onfluorided alumina is described in U.S. Pat. No. 4,873,381, which isincorporated herein by reference.

By a catalytically effective amount is meant the concentration ofcatalysts on the support that is sufficient to carry out the catalyticreaction. The concentration of palladium on the support is typically inthe range of from about 0.1% to about 10% by weight based on the totalweight of the catalyst and is preferably in the range of about 0.1% toabout 5% by weight based on the total weight of the catalyst. Theconcentration of the additional Group VIII metal, when used, is about 3%by weight, or less, based on the total weight of the catalyst; butpalladium is ordinarily at least 50% by weight based on the weight ofthe total metals present on the support, and preferably at least 80% byweight based on the weight of the total metals present on the support.

The relative amount of hydrogen fed during contact of CFC-215bb in areaction zone containing the palladium-containing catalyst is from about1 mole of H₂ per mole of CFC-215bb to about 5 moles of H₂ per mole ofCFC-215bb, preferably from about 1 mole of H₂ per mole of CFC-215bb toabout 4 moles of H₂ per mole of CFC-215bb and more preferably from about1.0 mole of H₂ per mole of CFC-215bb to about 3 moles H₂ per mole ofCFC-215bb.

The reaction zone temperature for the catalytic hydrogenation ofCFC-215bb is typically in the range of from about 100° C. to about 400°C., and preferably is in the range of from about 125° C. to about 350°C. The contact time is typically in the range of from about 1 to about450 seconds, and preferably is in the range of from about 10 to about120 seconds. The reactions are typically conducted at atmosphericpressure or superatmospheric pressure.

The effluent from the reaction zone typically includes HCl, unreactedhydrogen, HF, HFC-1225ye, CF₃CF═CH₂ (HFC-1234yf) and CF₃CHFCH₂F(HFC-245eb), higher boiling products and intermediates typicallyincluding CF₃CHFCH₂Cl (HCFC-244eb), CF₃CClFCH₂F (HCFC-235bb) andCF₃CF═CFCl (CFC-1215yb) and any unconverted CFC-215bb.

Through proper selection of operating conditions such as temperature,contact time and hydrogen to CFC-215bb ratios, the process of theinvention may be operated to produce predominantly mixtures ofCFC-1215yb and HFC-1225ye. The CFC-1215yb produced by the process ofthis invention is a useful starting material for the manufacture of thesaturated hydrofluorocarbon HFC-245eb.

In accordance with this invention, HF may also be fed in the reactionzone. Of note are embodiments wherein said HF is fed to the reactionzone as an azeotrope or near azeotrope comprising HF and CFC-215bb.

When HF is co-fed along with hydrogen and CFC-215bb to the reaction zonecontaining the palladium-containing catalyst at elevated temperature(e.g., about 250° C. or higher), the effluent from the reaction zonenormally contains CF₃CFHCF₂Cl (HCFC-226ea) in addition to thosecompounds present in the product mixture when no HF is present in thefeed to the reaction zone (e.g. CFC-1215yb). Accordingly, this inventionprovides a process for the preparation of a product mixture comprisingHFC-1225ye and HCFC-226ea from CFC-215bb by reacting CFC-215bb withhydrogen in the presence of hydrogen fluoride. Of note are embodimentswherein HFC-226ea is present in the product mixture; and whereinHFC-226ea is recovered from the product mixture. The HCFC-226ea can befurther processed to produce products containing no chlorine. Of noteare embodiments wherein HF is fed to the reaction zone and HFC-1225ye,HCFC-226ea and CFC-1215yb are all present in the product mixture.

When the production of HCFC-226ea is desired, the relative amount of HFfed to the reaction zone is typically from about 1 to 10 moles of HF permole of hydrogen fed to the reaction zone and is preferably from about 2to 8 moles of HF per mole of hydrogen fed to the reaction zone.

When the production of HCFC-226ea is desired, the reaction zonetemperature for the catalytic hydrogenation of CFC-215bb in the presenceof HF is typically in the range of from about 250° C. to about 400° C.,and preferably is in the range of from about 300° C. to about 375° C.The contact time is typically in the range of from about 1 to about 450seconds, and preferably is in the range of from about 10 to about 120seconds. The reactions are typically conducted at atmospheric pressureor superatmospheric pressure.

When HF is co-fed along with hydrogen and CFC-215bb to the reaction zonecontaining the palladium-containing catalyst at temperature of less thanabout 250° C., the effluent from the reaction zone normally containsHFC-245eb in addition to those compounds present in the product mixturewhen no HF is present in the feed to the reaction zone (e.g.CFC-1215yb). Accordingly, this invention provides a process for thepreparation of a product mixture comprising HFC-1225ye and HFC-245ebfrom CFC-215bb by reacting CFC-215bb with hydrogen in the presence ofhydrogen fluoride. Of note are embodiments wherein HFC-245eb is presentin the product mixture; and wherein said HFC-245eb is recovered from theproduct mixture.

When the production of HFC-245eb is desired, the presence of HF is notcritical. If used, the relative amount of HF fed to the reaction zone istypically from about 10 moles of HF per mole of hydrogen fed to thereaction zone or less.

When the production of HFC-245eb is desired, the reaction zonetemperature for the catalytic hydrogenation of CFC-215bb in the presenceor absence of HF is typically in the range of from about 100° C. toabout 250° C., and is preferably in the range of from about 125° C. toabout 225° C. The contact time is typically in the range of from about 1to about 450 seconds, and preferably is in the range of from about 10 toabout 120 seconds. The reactions are typically conducted at atmosphericpressure or superatmospheric pressure.

Through proper selection of operating conditions such as temperature,contact time and hydrogen to hydrogen fluoride ratios, the process maybe operated to produce a product mixture wherein the halogenatedhydrocarbons comprise predominantly of CFC-1215yb, HCFC-226ea andHFC-1225ye. Alternatively, through proper selection of operatingconditions such as temperature, contact time and hydrogen to hydrogenfluoride ratios, the process may be operated to produce a productmixture wherein the halogenated hydrocarbons comprise predominantly ofCFC-1215yb, HFC-245eb and HFC-1225ye.

Of note are embodiments where HFC-1225ye is a desired product, and isrecovered from the product mixture. The HFC-1225ye present in theeffluent from the reaction zone may be separated from the othercomponents of the product mixture and unreacted starting materials byconventional means (e.g., distillation). When HF is present in theeffluent, this separation can also include isolation of azeotrope ornear azeotrope of HFC-1225ye and HF and further processing to produceHF-free HFC-1225ye by using procedures similar to that disclosed in USPatent Publication US 2006/0106263 A1, which is incorporated herein byreference.

Also of note are embodiments where HFC-1234yf is present in the productmixture and is recovered therefrom. When HFC-1234yf is present in theeffluent from the reaction zone, it may also be separated from the othercomponents of the product mixture and unreacted starting materials byconventional means (e.g., distillation). When HF is present in theeffluent, this separation can also include isolation of azeotrope ornear azeotrope of HFC-1234yf and HF and further processing to produceHF-free HFC-1234yf by using procedures similar to that disclosed in USPatent Publication US 2006/0106263 A1.

Of note are embodiments wherein HFC-245eb is present in the productmixture; and wherein said HFC-245eb is recovered. When HFC-245eb ispresent in the effluent from the reaction zone, it may also be separatedfrom the other components of the product mixture and unreacted startingmaterials by conventional means (e.g., distillation). When HF is presentin the effluent, this separation can also include isolation of theazeotrope or near azeotrope of HFC-245eb and HF and further processingto produce HF-free HFC-245eb by using procedures similar to thosedisclosed in US Patent Publication US 2006/0106263 A1. Of note areembodiments wherein HF is fed to the reaction zone and HFC-245eb ispresent in the product mixture, and wherein at least a portion ofHFC-245eb is recovered from the product mixture as an azeotropecomprising HF and HFC-245eb. The HFC-245eb/HF azeotrope can be recycledback to the reactor.

Of note are embodiments wherein CFC-1215yb is present in the productmixture; and wherein said CFC-1215yb is recovered. The CFC-1215ybproduced by the processes above can be used as a starting material forthe manufacture of the saturated hydrofluorocarbon HFC-245eb byhydrogenation (optionally in the presence of HF). Thus, the presentinvention also provides a process for making HFC-245eb and HFC-1225ye,comprising: (a) reacting CFC-215bb with hydrogen, optionally in thepresence of HF, in a reaction zone in the presence of a catalystcomprising a catalytically effective amount of palladium supported on asupport selected from the group consisting of alumina, fluoridedalumina, aluminum fluoride and mixtures thereof to produce a productmixture comprising CFC-1215yb and HFC-1225ye (wherein the mole ratio ofH₂ to CFC-215bb fed to the reaction zone is between about 1:1 and about5:1); (b) recovering said CFC-1215yb; (c) hydrogenating said CFC-1215yb,optionally in the presence of HF, to HFC-245eb; and (d) recoveringHFC-245eb.

The HFC-1225ye produced by the processes above can be used as a startingmaterial for the manufacture of the saturated hydrofluorocarbonHFC-245eb by hydrogenation (optionally in the presence of HF). Thus, thepresent invention also provides another process for making HFC-245eb,comprising: (a) reacting CFC-215bb with hydrogen, and optionally in thepresence of HF, in a reaction zone in the presence of a catalystcomprising a catalytically effective amount of palladium supported on asupport selected from the group consisting of alumina, fluoridedalumina, aluminum fluoride and mixtures thereof to produce a productmixture comprising HFC-1225ye (wherein the mole ratio of H₂ to CFC-215bbfed to the reaction zone is between about 1:1 and about 5:1); (b)recovering said HFC-1225ye; and (c) hydrogenating said HFC-1225ye,optionally in the presence of HF, to HFC-245eb.

The present invention also provides a process for making1,1,1,2,3,3-hexafluoropropane (HFC-236ea), comprising: (a) reactingCFC-215bb with hydrogen and hydrogen fluoride in a reaction zone in thepresence of a catalyst comprising a catalytically effective amount ofpalladium supported on a support selected from the group consisting ofalumina, fluorided alumina, aluminum fluoride and mixtures thereof toproduce a product mixture comprising HCFC-226ea in addition toHFC-1225ye (wherein the mole ratio of H₂ to CFC-215bb fed to thereaction zone is between about 1:1 and about 5:1); (b) recovering saidHCFC-226ea; and (c) hydrogenating said HCFC-226ea to HFC-236ea.

In the above processes for making HFC-245eb or HFC-236ea, the step (a)of the process is conducted under conditions as described above formaking HFC-1225ye from CFC-215bb by reacting with hydrogen, optionallyin the presence of HF.

In the above processes for making HFC-245eb or HFC-236ea, the step (c)of the process, i.e. the reaction of HCFC-226ea, CFC-1215yb orHFC-1225ye with hydrogen, optionally in the presence of HF, is carriedout in the presence of a hydrogenation catalyst. Hydrogenation catalystssuitable for use in this invention include catalysts comprising at leastone metal selected from the group consisting of rhenium, iron,ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, andplatinum. Said catalytic metal component is typically supported on acarrier such as carbon or graphite or a metal oxide, fluorinated metaloxide, or metal fluoride where the carrier metal is selected from thegroup consisting of magnesium, aluminum, titanium, vanadium, chromium,iron, and lanthanum. Of note are palladium catalysts supported on carbon(see e.g., U.S. Pat. No. 5,523,501, the teachings of which areincorporated herein by reference).

Also of note are carbon-supported catalysts in which the carbon supporthas been washed with acid and has an ash content below about 0.1% byweight. Hydrogenation catalysts supported on low ash carbon aredescribed in U.S. Pat. No. 5,136,113, the teachings of which areincorporated herein by reference. Also of note are catalysts comprisingat least one metal selected from the group consisting of palladium,platinum, and rhodium supported on alumina (Al₂O₃), fluorinated alumina,or aluminum fluoride (AlF₃) and mixtures thereof.

The relative amount of hydrogen contacted with HCFC-226ea, CFC-1215yb orHFC-1225ye, optionally in the presence of HF, when a hydrogenationcatalyst is used is typically from about the stoichiometric ratio ofhydrogen to the fluorinated organic starting materials to about 10 molesof H₂ per mole of the fluorinated organic starting materials. Suitablereaction temperatures are typically from about 100° C. to about 350° C.,preferably from about 125° C. to about 300° C. The contact time istypically from about 1 to about 450 seconds, preferably from about 10 toabout 120 seconds. The reactions are typically conducted at atmosphericpressure or superatmospheric pressure.

The reactor, distillation columns, and their associated feed lines,effluent lines, and associated units used in applying the processes ofthis invention should be constructed of materials resistant to hydrogenfluoride and hydrogen chloride. Typical materials of construction,well-known to the fluorination art, include stainless steels, inparticular of the austenitic type, the well-known high nickel alloys,such as Monel™ nickel-copper alloys, Hastelloy™ nickel-based alloys and,Inconel™ nickel-chromium alloys, and copper-clad steel.

The present invention also provides azeotrope or near azeotropecompositions comprising an effective amount of hydrogen fluoridecombined with a compound selected from CFC-215bb and HFC-245eb.

In connection with developing processes for the separation of theindividual compounds from the reaction zone effluent from the reactionof CFC-215bb with hydrogen or with hydrogen and hydrogen fluoride, it isnoted that CFC-215bb and HFC-245eb (as well as HFC-1225ye andHFC-1234yf) each can be present as their respective azeotrope or nearazeotrope with HF. HF can come from the products of dehydrofluorinationreactions of HFC-245eb or intermediates containing five fluorines tocompounds containing at least one less fluorine or from HF co-fed alongwith hydrogen to the reaction zone.

By effective amount is meant an amount, which, when combined withHFC-245eb or CFC-215bb, results in the formation of their respectiveazeotrope or near azeotrope mixture. As recognized in the art, anazeotrope or a near azeotrope composition is an admixture of two or moredifferent components which, when in liquid form under a given pressure,will boil at a substantially constant temperature, which temperature maybe higher or lower than the boiling temperatures of the individualcomponents, and which will provide a vapor composition essentiallyidentical to the liquid composition undergoing boiling.

For the purpose of this discussion, near azeotrope composition (alsocommonly referred to as an “azeotrope-like composition”) means acomposition that behaves like an azeotrope (i.e., has constant boilingcharacteristics or a tendency not to fractionate upon boiling orevaporation). Thus, the composition of the vapor formed during boilingor evaporation is the same as or substantially the same as the originalliquid composition. Hence, during boiling or evaporation, the liquidcomposition, if it changes at all, changes only to a minimal ornegligible extent. This is to be contrasted with non-near azeotropecompositions in which during boiling or evaporation, the liquidcomposition changes to a substantial degree.

Additionally, near azeotrope compositions exhibit dew point pressure andbubble point pressure with virtually no pressure differential. That isto say that the difference in the dew point pressure and bubble pointpressure at a given temperature will be a small value. In thisinvention, compositions with a difference in dew point pressure andbubble point pressure of less than or equal to 3 percent (based upon thebubble point pressure) are considered to be near azeotropes.

Accordingly, the essential features of an azeotrope or a near azeotropecomposition are that at a given pressure, the boiling point of theliquid composition is fixed and that the composition of the vapor abovethe boiling composition is essentially that of the boiling liquidcomposition (i.e., no fractionation of the components of the liquidcomposition takes place). It is also recognized in the art that both theboiling point and the weight percentages of each component of theazeotrope composition may change when the azeotrope or near azeotropeliquid composition is subjected to boiling at different pressures. Thus,an azeotrope or a near azeotrope composition may be defined in terms ofthe unique relationship that exists among the components or in terms ofthe compositional ranges of the components or in terms of exact weightpercentages of each component of the composition characterized by afixed boiling point at a specified pressure. It is also recognized inthe art that various azeotrope compositions (including their boilingpoints at particular pressures) may be calculated (see, e.g., W. SchotteInd. Eng. Chem. Process Des. Dev. (1980) 19, 432-439). Experimentalidentification of azeotrope compositions involving the same componentsmay be used to confirm the accuracy of such calculations and/or tomodify the calculations at the same or other temperatures and pressures.

In accordance with this invention, compositions are provided whichcomprise CFC-215bb and HF wherein HF is present in an effective amountto form an azeotropic combination with the CFC-215bb. These includecompositions comprising from about 98.2 mole percent to about 78.0 molepercent HF and from about 1.8 mole percent to about 22.0 mole percentCFC-215bb (which form azeotropes boiling at a temperature from betweenabout −20° C. and about 140° C. and at a pressure from between about3.05 psi (21.0 kPa) and about 951 psi (6557 kPa)).

Additionally, near azeotrope compositions containing HF and CFC-215bbmay also be formed. Such near azeotrope compositions exist aroundazeotrope compositions. For example, a composition comprising 98.2 molepercent HF and 1.8 mole percent CFC-215bb is an azeotrope composition at−20° C. at 3.05 psi (21.0 kPa). Compositions comprising from about 99.0mole percent to about 98.15 mole percent HF and from about 1.0 molepercent to about 1.85 mole percent CFC-215bb are near azeotropecompositions. Similarly, at 80° C. and 112.2 psi (773.6 kPa), acomposition comprising 91.1 mole percent HF and 8.9 mole percentCFC-215bb is an azeotrope composition, and compositions comprising fromabout 90.6 mole percent to about 92.4 mole percent HF and from about 9.4mole percent to about 7.6 mole percent CFC-215bb are near azeotropecompositions. Also, at 140° C. and 951 psi (6557 kPa), a compositioncomprising 78.0 mole percent HF and 22.0 mole percent CFC-215bb is anazeotrope composition, and compositions comprising from about 77.2 molepercent to about 78.4 mole percent HF and from about 22.8 mole percentto about 21.6 mole percent CFC-215bb are near azeotrope compositions.

Compositions may be formed that consist essentially of azeotropecombinations of hydrogen fluoride with CFC-215bb. These includecompositions consisting essentially of from about 98.2 mole percent toabout 78.0 mole percent HF and from about 1.8 mole percent to about 22.0mole percent CFC-215bb (which forms an azeotrope boiling at atemperature from between about −20° C. and about 140° C. and at apressure from between about 3.05 psi (21.0 kPa) and about 951 psi (6557kPa)).

At atmospheric pressure, the boiling points of hydrogen fluoride andCFC-215bb are about 19.5° C. and −20° C., respectively. The ratio ofrelative volatility at 16.76 psi (111.5 kPa) and 20.0° C. of HF toCFC-215bb was found to be nearly 1.0 as 96.2 mole percent HF and 3.8mole percent CFC-215bb was approached. The ratio of relative volatilityat 84.81 psi (585.1 kPa) and 70.0° C. was found to be nearly 1.0 as 92.1mole percent HF and 7.9 mole percent CFC-215bb was approached. Thesedata indicate that the use of conventional distillation procedures willnot result in the separation of a substantially pure compound because ofthe low difference of relative volatility of the compounds.

To determine the relative volatility of HF with CFC-215bb, the so-calledPTx Method was used. In this procedure, the total absolute pressure in acell of known volume is measured at a constant temperature for variousknown binary compositions. Use of the PTx Method is described in greaterdetail in “Phase Equilibrium in Process Design”, Wiley-IntersciencePublisher, 1970, written by Harold R. Null, on pages 124 to 126, theentire disclosure of which is hereby incorporated by reference. Samplesof the vapor and liquid, or vapor and each of the two liquid phasesunder those conditions where two liquid phases exist, were obtained andanalyzed to verify their respective compositions.

These measurements can be reduced to equilibrium vapor and liquidcompositions in the cell by an activity coefficient equation model, suchas the Non-Random, Two-Liquid (NRTL) equation, to represent liquid phasenon-idealities. Use of an activity coefficient equation, such as theNRTL equation, is described in greater detail in “The Properties ofGases and Liquids”, 4^(th) Edition, publisher McGraw Hill, written byReid, Prausnitz and Poling, on pages 241 to 387; and in “PhaseEquilibria in Chemical Engineering”, published by ButterworthPublishers, 1985, written by Stanley M. Walas, pages 165 to 244; theentire disclosure of each of the previously identified references arehereby incorporated by reference.

Without wishing to be bound by any theory or explanation, it is believedthat the NRTL equation can sufficiently predict whether or not mixturesof HF and CFC-215bb behave in an ideal manner, and can sufficientlypredict the relative volatilities of the components in such mixtures.Thus, while HF has a good relative volatility compared to CFC-215bb athigh CFC-215bb concentrations, the relative volatility becomes nearly1.0 as 3.8 mole percent CFC-215bb was approached at 20.0° C. This wouldmake it impossible to separate CFC-215bb from HF by conventionaldistillation from such a mixture. Where the ratio of relative volatilityapproaches 1.0 defines the system as forming a near-azeotrope. Where theratio of relative volatility is 1.0 defines the system as forming anazeotrope.

It has been found that azeotropes of CFC-215bb and HF are formed at avariety of temperatures and pressures. Azeotrope compositions may beformed between 21.0 kPa (at a temperature of −20° C.) and 6557 kPa (at atemperature of 140° C.) when said compositions consisting essentially ofCFC-215bb and HF range from about 98.2 mole percent HF (and 1.8 molepercent CFC-215bb) to about 78.0 mole percent HF (and 22.0 mole percentCFC-215bb). An azeotrope of HF and CFC-215bb has been found at 20.0° C.and 16.76 psi (111.5 kPa) consisting essentially of about 96.2 molepercent HF and about 3.8 mole percent CFC-215bb. An azeotrope of HF andCFC-215bb has also been found at 70.0° C. and 84.81 psi (585.1 kPa)consisting essentially of about 92.1 mole percent HF and about 7.9 molepercent CFC-215bb. Based upon the above findings, azeotrope compositionsat other temperatures and pressures may be calculated. It has beencalculated that an azeotrope composition of about 98.2 mole percent HFand about 1.8 mole percent CFC-215bb can be formed at −20° C. and 3.05psi (21.0 kPa) and an azeotrope composition of about 78.0 mole percentHF and about 22.0 mole percent CFC-215bb can be formed at 140° C. and951 psi (6557kPa). Accordingly, the present invention provides azeotropecompositions consisting essentially of from about 98.2 mole percent toabout 78.0 mole percent HF and from about 1.8 mole percent to about 22.0mole percent CFC-215bb, said composition having a boiling point of about−20° C. at about 3.05 psi (21.0 kPa) to about 140° C. at about 951 psi(6557 kPa).

The HF/CFC-215bb azeotrope and near azeotrope compositions in theeffluent from the reaction zone can be recycled back to the reactionzone and are useful in processes to produce HFC-245eb and HFC-1225ye andin processes to produce HCFC-226ea.

In accordance with this invention, compositions are provided whichcomprise HFC-245eb and HF wherein HF is present in an effective amountto form an azeotropic combination with the HFC-245eb. According tocalculations, these include compositions comprising from about 81.0 molepercent to about 55.0 mole percent HF and from about 19.0 mole percentto about 45.0 mole percent HFC-245eb (which form azeotropes boiling at atemperature of from about −20° C. to about 135° C. and at a pressure offrom about 4 psi (27.5 kPa) to about 550 psi (3792 kPa)).

The following specific Examples are to be construed as merelyillustrative, and do not constrain the remainder of the disclosure inany way whatsoever.

EXAMPLES General Procedure for the Preparation of Palladium on FluoridedAlumina Catalyst

A weighed quantity of the catalyst was placed in a ⅝ inch (1.58 cm)diameter Inconel™ nickel alloy reactor tube heated in a fluidized sandbath. The tube was heated from 50° C. to 175° C. in a flow of nitrogen(50 cc/min; 8.3×10⁻⁷ m³/sec) over the course of about one hour. HF wasthen admitted to the reactor at a flow rate of 50 cc/min (8.3×10⁻⁷m³/sec).

After 0.5 to 2 hours the nitrogen flow was decreased to 20 cc/min(3.3×10⁻⁷ m³/sec) and the HF flow increased to 80 cc/min (1.3×10⁻⁶m³/sec); this flow was maintained for about 1 hour. The reactortemperature was then gradually increased to 400° C. over 3 to 5 hours.At the end of this period, the HF flow was stopped and the reactorcooled to the desired operating temperature under 20 sccm (3.3×10⁻⁷m³/sec) nitrogen flow. The fluorided alumina was discharged from thereactor for further use or kept in the reactor for catalyst evaluation.

General Procedure for Product Analysis

The following general procedure is illustrative of the method used foranalyzing the products of fluorination reactions. Part of the totalreactor effluent was sampled on-line for organic product analysis usinga gas chromatograph equipped a mass selective detector (GC/MS). The gaschromatography utilized a 20 ft. (6.1 m) long×⅛ in. (0.32 cm) diametertube containing Krytox® perfluorinated polyether on an inert carbonsupport. The helium flow was 30 mL/min (5.0×10⁻⁷ m³/sec). Gaschromatographic conditions were 60° C. for an initial hold period ofthree minutes followed by temperature programming to 200° C. at a rateof 6° C./minute.

LEGEND 1234yf is CF₃CF═CH₂ 1243zf is CF₃CH═CH₂ 263fb is CF₃CH₂CH₃ 245ebis CF₃CHFCH₂F 235bb is CF₃CFClCH₂F 226ea is CF₃CHFCF₂Cl 244eb isCF₃CFHCH₃ 215bb is CF₃CFClCFCl₂ 1225ye is E and Z forms of CF₃CF═CHF1215yb is E and Z forms of CF₃CF═CFCl

Example 1 Reaction of H₂ and HF with CFC-215bb Over Palladium onFluorided Alumina Catalyst

A 10.0 g (15 ml) sample of 1% palladium on fluorided alumina catalyst(⅛″ extrudates) prepared according to the General Procedure describedabove for preparation of the catalyst, was placed in a ⅝ inch (1.58 cm)diameter Inconel™ nickel alloy reactor tube heated in a fluidized sandbath. The CFC-215bb was fed from a pump to a vaporizer maintained atabout 100-110° C. The vapor was combined with the appropriate molarratios of HF and hydrogen in a 0.5″ (1.27 cm) diameter Monel™ nickelalloy tube packed with Monel™ turnings. The mixture of reactants thenentered the reaction zone containing the catalyst. The reactions wereconducted at a nominal pressure of one atmosphere. Product analysis wasperformed as described in the General Procedure for product analysis.The results of the reaction of hydrogen and hydrogen fluoride withCF₃CFClCFCl₂ over this catalyst at various temperatures are shown inTable 1. Small amounts of other products, not included in Table 1 werealso present. The product analytical data is given in units of GC area%. The contact time was 30 seconds except for the last three runsindicated in Table 1.

TABLE 1 Mol. Ratio Z- E- Z or E- E or Z- T ° C. H₂/215bb/HF 1234yf1243zf 263fb 1225ye 1225ye 245eb 1215yb 1215yb 226ea 215bb 225 2/1/4 2.6ND 1.6 16.7 18.0 29.3 5.6 4.3 ND 13.2 250 2/1/4 3.2 ND 1.8 21.4 20.920.5 8.5 6.6 ND 9.3 275 2/1/4 3.1 2.5 2.1 44.6 10.5 14.8 5.9 4.5 ND 2.7300 2/1/4 3.1 2.8 1.9 43.8 10.7 2.5 10.4 4.7 ND 2.3 300 4/1/8 16.3 0.17.9 28.8 7.3 24.7 ND ND ND ND 300 1/1/8 0.7 1.2 ND 16.0 4.4 ND 19.0 9.19.3 33.7 350 1/1/8 0.7 1.2 ND 9.6 1.4 ND 13.8 6.1 21.3 29.4 350 2/1/83.6 1.4 ND 28.5 8.8 ND 15.3 7.1 17.0 3.8 ND = not detected

Example 2 Reaction of H2 with CFC-215bb Over Palladium on AluminaCatalyst

A Hastelloy tube (0.625″ OD×0.576 ID×10″L) was filled with 15cc (9.7 g)of commercial 1% palladium on alumina spheres (4 mm). The packed portionof the reactor was heated by a 5.7″×1″ ceramic band heater clamped tothe outside of the reactor. A thermocouple, positioned between thereactor wall and the heater, measured the reactor temperature. Thecatalyst was activated by heating at 250° C. for 2 hours with 50 sccm(8.33×10⁻⁷ m³/s) of nitrogen. The nitrogen was turned off and thecatalyst was treated with 50 sccm (8.33×10⁻⁷ m³/s) of hydrogen at 250°C. for two hours. The reactor was then cooled to the desired operatingtemperature under a flow of nitrogen. A flow of hydrogen and CFC-215bbwas then started through the reactor after stopping the nitrogen flow.The hydrogen to CFC-215bb mole ratio was 2/1 and the contact time was 30seconds. The products were analyzed by GC/MS and are reported in Table 2as mole %. Minor amounts of other compounds, not listed in Table 2 werealso present.

TABLE 2 Z- E- Z or E- E or Z- T ° C. 1234yf 1225ye 1225ye 245eb 235bb1215yb 1215yb 244eb 215bb 175 7.0 25.6 24.1 8.9 7.4 5.2 3.8 14.1 1.0 2504.3 33.4 14.7 1.4 2.0 16.7 8.7 6.4 0.4

Comparative Example

Reaction of H2 with CFC-215bb over Palladium on Carbon catalyst Example1 was substantially repeated except that the catalyst was commercial0.5% palladium on carbon (5.4 g, 15.0 ml) and only hydrogen andCFC-215bb were fed to the reactor. The hydrogen to CFC-215bb mole ratiowas 2/1 and the contact time was 30 seconds. The GC/MS analyticalresults of the products, in area %, for various operating temperaturesare summarized in Table 3. Minor amounts of other compounds, not listedin Table 3 were also present.

TABLE 3 T ° C. 263fb 254eb 245eb 235bb 150 0.1 9.4 83.2 7.0 175 0.2 8.582.3 5.8 225 0.6 10.7 87.2 0.1

What is claimed is:
 1. A composition comprising: (a)1,1,1,2,3-pentafluoropropane and (b) HF; wherein the HF is present in aneffective amount to form an azeotropic combination with the1,1,1,2,3-pentafluoropropane.
 2. An azeotropic composition as in claim1, comprising from about 81.0 mole percent to about 55.0 mole percent HFand from about 19.0 mole percent to about 45.0 mole percent1,1,1,2,3-pentafluoropropane.
 3. An azeotropic composition as in claim 1comprising comprising from about 81.0 mole percent to about 55.0 molepercent HF and from about 19.0 mole percent to about 45.0 mole percent1,1,1,2,3-pentafluoropropane. which form azeotropes boiling at atemperature of from about −20° C. to about 135° C. and at a pressure offrom about 4 psi (27.5 kPa) to about 550 psi (3792 kPa).